Which of the following gives the crushing energy required to create new surface ?

Related Mcqs:

1. For crushing of solids, the Rittinger’s law states that the work required for crushing is proportional to __________________?

   A. The new surface created
   B. The size reduction ratio
   C. The change in volume due to crushing
   D. None of these

2. Which of the following equations is Rittinger’s crushing law? (Where P = power required by the machine, m = feed rate, k = a constant, D̅ sa & D̅ sb = volume surface mean diameter of feed & product respectively) ?

   A. P/m = K/ √Dp
   B. P/m = K . ln D̅ sa/D̅ sb
   C. P/m = K . (1/ D̅ sb – 1/D̅ sa)
   D. None of these

3. In a size reduction crushing operation, feed size is 300 to 1500 mm while the product size is 100 to 300 mm. This is a case of the ________________ crushing?

   A. Secondary
   B. Fine
   C. Primary
   D. Ultrafine

4. In a size reduction crushing operation, feed size is 100 to 300 mm. while the product size is 10 to 50 mm. This is a case of the _____________ crushing?

   A. Primary
   B. Secondary
   C. Fine
   D. Ultrafine

5. General crushing equation is given by d(P/m) = -K (dD̅ S/D̅ n S). Bond’s crushing law is obtained by solving this equation for n = _____________ and feed of infinite size?

   A. 1
   B. 1.5
   C. 2
   D. 2.5

6. In a size reduction crushing operation, the feed size is 10 to 50 mm, while the product size is 2 to 10 mm. This is a case of _______________ crushing?

   A. Primary
   B. Secondary
   C. Fine
   D. Ultrafine

7. What is the usual value of angle of nip for crushing of ordinary rock in smooth steel crushing rolls?

   A. 16°
   B. 32°
   C. 40°
   D. 46°

8. According to Bond crushing law, the work required to form particle of size ‘D’ from very large feed is (where (S/V)p and (S/V)f are surface to volume ratio of the product and feed respectively) ?

   A. (S/V)p
   B. √(S/V)p
   C. (S/V)2p
   D. (S/V)f

9. Energy consumed for crushing one ton of material ranges from ______________ kWh?

   A. 0.01 to 0.1
   B. 0.5 to 1.5
   C. 2 to 3.5
   D. 4 to 5

10. The energy required per unit mass to grind limestone particles of very large size to 100 μm is 12.7 kWh/ton. An estimate (using Bond’s law) of the energy to grind the particles from a very large size to 50 μm is________________?

    A. 6.35 kWh/ton
    B. 9.0 kWh/ton
    C. 18 kWh/ton
    D. 25.4 kWh/ton